In summary, we believe that in the IBS-D visceral hypersensitivity rat model, the diversity of intestinal flora is changed, the number of probiotics such as Bifidobacterium and Lactobacillus is reduced, while the content of pathogenic flagellated bacteria were increased, the content of flagellin and the expression of TLR5 on colonic mucosa enhanced, resulting in chronic inflammatory and abnormal immune response in the mucosa and inducing the occurrence of visceral hypersensitivity. This evidence concerns the gene TLR5 and hypersensitivity.